It is often necessary in a container manufacturing plant to convey containers from a mass into single file and to convey the single file containers at a desired predetermined speed. A problem associated with conventional air conveying equipment for conveying containers in single file is that the speed is not easily controlled and, in fact, the containers tend to reach extremely high speeds if uncontrolled, resulting in damage to the containers. Also, when the containers strike each other at high speed one or more of the containers may be upset causing the line of containers to jam. There is an ever increasing volume of air moving in the downstream direction from the upstream end of the conveyor to the downstream end. This causes the containers to tend to reach a terminal velocity, if not restrained, which may be substantially equal to the velocity of the air passing through the louvers or air jets supplying air to the conveying surface.
The mass of containers need to be fed into single file for supplying the containers to decorators, base coaters, and other apparatus in the plant which must perform an operation on or with respect to the container.
One such single filing apparatus is disclosed in my U.S. Pat. No. 4,462,720 for "Air Table System". This device supports containers on a table by a layer of air provided by air jets slanted in the downstream direction toward a single file conveying zone. An imperforate cover is placed above the surface of the table a distance slightly greater than the longitudinal dimension of the containers being transported and is positioned over at least a portion of the single file conveying zone. Blow-back jets are connected to a source of air under pressure for supplying air in the single file conveying zone in opposition to the direction of normal flow of the objects. By use of this apparatus, a mass of containers can be rearranged into single file arrangement for discharge at the downstream end of the table.
Another single filer is shown in my U.S. Pat. No. 4,561,806 for "Vertical Single Filer Conveyor System". In this apparatus, containers are fed from a mass of containers onto a table which has at least three zones extending from an upstream location. The containers are supported and moved by a prearranged pattern of flotation air jets. In addition, a row of acceleration jets, which are larger in size than the flotation jets, are located in the table adjacent to and spaced in parallel relation to converging sides of the table to form two converging rows of acceleration jets. Means is provided to incrementally increase the volume and velocity of air through the acceleration jets between each of the three zones from the upstream location to the downstream location to accelerate and longitudinally separate the objects as they move along the table from the upstream location to the downstream location so that the converging of the sides coacts with the acceleration jets to converge longitudinally separated containers in a prearranged pattern to bring them into single file. This device has been found to be very satisfactory for placing smooth decorated containers in single file at relatively high speed.
None of these devices provide for controlling the speed of the containers as they move in single file along the conveyor.